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headlights sometimes do not work


Full Member
Feb 13, 2007
Collierville, TN
Hey guys

Thought I would ask y'all this question.? I looked at some threads about headlight problems but saw nothing.? I got in my truck the other night and tried to leave and noticed my headlights were not on.? I checked my parking brake and it was not set.? I tried to turn them on manually and they would not.? I checked all the fuses and relays that dealt with DRLs and lighting.? Found nothing faulty.? I then started the truck. The headlights worked.? I went on my way.? Later that night I got ready to go home and they did not work? however my foglights did.? I started to drive home by foglights.? In the middle of the drive they came back on.? The next day I changed out the DRL relay to see if that would correct the problem.? I thought it did but that night the lights were again delayed in the activation of the headlights from DRLs.? What else could it be?

Any input would be great.


bulbs, socket, &/or wiring
Thanks for responding.  Yeah I jiggled some wires and had no changes and looked at the bulbs themselves and they were fine.
Hi Andrefire, sorry to hear about your lighting malfunction, but if your DLR lights come on then that means that you might have a sensor problem. but then again you are saying you try them manually and nothing happen.. May be could it be a switch and/or  sensor problem, but somewhere here I found once a schematic on the headlight sensor that maybe u can use to test that sensor up. I am gonna try find the link and see if I can find it or if some one please help this brother in need out. Thanls and hope you problem is fixed by now.
Thanks.  Since my last post it has not happened again.  I did nothing else to the truck but drive it.  So I do not know if it was just a stroke of good luck that it has not happened again or what.  But I will appreciate any insight for future reference.
  had a weird experience with the Trailblazer the other day.  when i started the truck the lights did not come on automatically (it was dark out).  only the highbeams worked.  took truck to the dealer, and turned out all the bulbs were bad...  both headlight bulbs, parklights, and fog's.  go figure. ???
Thanks guys

It happened again a couple days ago. I had to turn on the fog lights.? About ten minutes into the dive they turned on.? I think I am gonna have to take it to a dealership and give them some of my hard earned money.? I hate doing that!? One thing I did notice is that the dashboard light activate like they are sopposed to.? Only the headlights and tail lights are slow to activate.? However, I have noticed that both the head and tail lights come on at the same time.? I am going to change out the bulbs and see if that corrects the problem.? Thanks for the help.

did you check the relays?
one for headlights I am sure...
Yeah there is a relay for the headlights labeled HDLP but since the tail lights are not working either I did not change it.  You think it could control both sets of lights?
I would check them all before I went to a dealer....

I would check fuses with ohm meter too...

andrefire said:
Ok.  I what is a ohm meter? I am a novice at this stuff.  And can I use it to check relays too?
a ohm meter checks resistance (a good fuse shouldn't have any)